Heating Unit Step Holder for Stable Terminal Contact
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Solution Overview
Problem
In fixing devices with a rotating belt interposed between a heater and a pressure roller, variations in contact pressure between the connector's terminal and supply terminal can cause connection faults due to differences in thickness between the heat conductive member and the supporting surfaces.
Innovation Solution
A heating unit design featuring a heater with a substrate, resistance heating elements, and a supply terminal, supported by a holder with a heat conductive sheet between the heater and the holder, where the holder's surfaces are positioned to create a step height greater than the heat conductive sheet's thickness, ensuring stable contact pressure and uniform temperature distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat conductive member with greater thickness is used, then heat conduction efficiency is improved, but connection reliability deteriorates due to large variations in contact pressure between terminal and supply terminal
Solution Approach 1:
The holder is divided into two distinct surfaces: a first surface that contacts the heat conductive member and a second surface that contacts the heater. This segmentation allows each surface to be optimized for its specific function - the first surface provides a stable contact area for thermal conduction while the second surface ensures reliable electrical connection, thereby resolving the contradiction between heat conduction efficiency and connection reliability
Solution Approach 2:
The solution introduces a dimensional approach by creating a step structure in the holder where the second surface is positioned at a different height than the first surface. This dimensional change allows the heat conductive member to maintain good thermal contact while the electrical connection is established at a different vertical level, preventing contact pressure variations that would compromise connection reliability
2Temperature
If the heat conductive member thickness exceeds the step height between surfaces, then thermal contact is improved, but space formation occurs between heater end and holder surface causing connection faults
Solution Approach 1:
The holder is pre-designed with a specific step height that is calculated to be greater than the thickness of the heat conductive member. This preliminary dimensional design ensures that when the heat conductive member is installed, it will make proper contact with the first surface while leaving sufficient space for the heater to contact the second surface, thereby preventing connection faults before they occur
Solution Approach 2:
Different regions of the holder are given different properties: the first surface area is designed for thermal contact with the heat conductive member, while the second surface area at a different height is designed for electrical contact with the heater. This local differentiation of functional properties allows both thermal efficiency and connection stability to be optimized simultaneously
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design suppresses variations in contact pressure, maintains uniform temperature across the heater, and prevents thermal expansion interference, ensuring reliable operation and efficient heat transfer.
Implementation Method 1
a resistance heating element provided on the substrate
Implementation Method 2
a heat conductive sheet located between the heater and the holder, the heat conductive sheet having a heat conductivity greater than that of the substrate
Data Source
AI summary
A heating unit includes a heater, an endless belt, a holder, a heat conductive sheet, and a connector including a connecting terminal connected to a supply terminal. The connector is configured to hold a first end of the heater in the longitudinal direction and a first end of the holder in the longitudinal direction. The holder includes a first surface supporting the heat conductive member, and a second surface supporting the first end of the heater. The second surface is located at a position nearer to the heater than the first surface in a direction orthogonal to the substrate. A height of a step formed between the first surface and the second surface is greater than a thickness of the heat conductive member.